System and method for using a network of thermostats as tool to verify peak demand reduction

ABSTRACT

The invention comprises systems and methods for estimating the rate of change in temperature inside a structure. At least one thermostat located is inside the structure and is used to control an climate control system in the structure. At least one remote processor is in communication with said thermostat and at least one database stores data reported by the thermostat. At least one processor compares the outside temperature at least one location and at least one point in time to information reported to the remote processor from the thermostat. The processor uses the relationship between the inside temperature and the outside temperature over time to derive a first estimation for the rate of change in inside temperature assuming that the operating status of the climate control system is “on”. The processor also uses the relationship between the inside temperature and the outside temperature over time to derive a second estimation for the rate of change in inside temperature assuming that the operating status of the climate control system is “off”. The compares at least one of the first estimation and the second estimation to the actual inside temperature recorded inside the structure to determine whether the actual rate of change in inside temperature is closer to the first estimation or the second estimation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/183,949, filed Jul. 31, 2008, which claims the benefit of priorityunder 35 U.S.C. §119(e) to both U.S. Provisional Application 60/963,183,filed Aug. 3, 2007; and U.S. Provisional Application No. 60/994,011,filed Sep. 17, 2007, the entireties of which are incorporated herein byreference and are to be considered part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the use of thermostatic HVAC controls that areconnected to a computer network as a part of a system for offering peakdemand reduction to electric utilities. More specifically, the presentinvention pertains to use of communicating thermostat combined with acomputer network to verify that demand reduction has occurred.

2. Background

Climate control systems such as heating and cooling systems forbuildings (heating, ventilation and cooling, or HVAC systems) have beencontrolled for decades by thermostats. At the most basic level, athermostat includes a means to allow a user to set a desiredtemperature, a means to sense actual temperature, and a means to signalthe heating and/or cooling devices to turn on or off in order to try tochange the actual temperature to equal the desired temperature. The mostbasic versions of thermostats use components such as a coiledbi-metallic spring to measure actual temperature and a mercury switchthat opens or completes a circuit when the spring coils or uncoils withtemperature changes. More recently, electronic digital thermostats havebecome prevalent. These thermostats use solid-state devices such asthermistors or thermal diodes to measure temperature, andmicroprocessor-based circuitry to control the switch and to store andoperate based upon user-determined protocols for temperature vs. time.

These programmable thermostats generally offer a very restrictive userinterface, limited by the cost of the devices, the limited real estateof the small wall-mounted boxes, and the inability to take into accountmore than two variables: the desired temperature set by the user, andthe ambient temperature sensed by the thermostat. Users can generallyonly set one series of commands per day, and to change one parameter(e.g., to change the late-night temperature) the user often has to cyclethrough several other parameters by repeatedly pressing one or twobuttons.

As both the cost of energy and the demand for electricity haveincreased, utilities supplying electricity increasingly face unpleasantchoices. The demand for electricity is not smooth over time. Inso-called “summer peaking” locations, on the hottest days of the year,peak loads may be twice as high as average loads. During such peak loadperiods (generally in the late afternoon), air conditioning can be thelargest single element of demand.

Utilities and their customers generally see reductions of supply(brownouts and blackouts) as an unacceptable outcome. But their otheroptions can be almost as distasteful. In the long term, they can buildadditional generating capacity, but that approach is very expensivegiven the fact that such capacity may be needed for only a few hours ayear. And this option is of course unavailable in the short term. Whenconfronted with an immediate potential shortfall, a utility may havereserve capacity it can choose to bring online. But because utilitiesare assumed to try to operate as efficiently as possible, the reservecapacity is likely to be the least efficient and most expensive and/ormore polluting plants to operate. Alternatively, the utility may seek topurchase additional power on the open market. But the spot market forelectricity, which cannot efficiently be stored, is extremely volatile,which means that spot prices during peak events may be as much as 10×the average price.

More recently, many utilities have begun to enter into agreements withcertain customers to reduce demand, as opposed to increasing supply. Inessence, these customers agree to reduce usage during a few criticalperiods in exchange for incentives from the utility. Those incentivesmay take the form of a fixed contract payment in exchange for the rightto cut the amount of power supplied at specified times, or a reducedoverall price per kilowatt-hour, or a rebate each time power is reduced,or some other method.

The bulk of these peak demand reduction (PDR) contracts have beenentered into with large commercial and industrial customers. This biasis in large part due to the fact that transaction costs are much lowertoday for a single contract with a factory that can offer demandreduction of 50 megawatts than they would be for the equivalent fromresidential customers—it could take 25,000 or more homes to equal thatreduction if these homes went without air conditioning.

But residential air conditioning is the largest single component of peakdemand in California, and is a large percentage in many other places.There are numerous reasons why it would be economically advantageous todeploy PDR in the residential market. Whereas cutting energy consumptionat a large factory could require shutting down or curtailing production,which has direct economic costs, cutting consumption for a couple ofhours in residences is likely to have no economic cost, and may onlyresult in minor discomfort—or none at all if no one is at home at thetime.

Residential PDR has been attempted. But there have been numerous commandand control issues with these implementations. The standard approach toresidential PDR has been to attach a radio-controlled switch to thecontrol circuitry located outside the dwelling. These switches aredesigned to receive a signal from a transmitter that signals thecompressor to shut off during a PDR call.

There are a number of technical complications with this approach. Thereis some evidence that “hard cycling” the compressor in this manner candamage the air conditioning system. There are also serious issuesresulting from the fact that the communication system is unidirectional.When utilities contract for PDR, they expect verification of compliance.One-way pagers allow the utility to send a signal that will shut of theA/C, but the pager cannot confirm to the utility that the A/C unit hasin fact been shut off. If a consumer tampers with the system so that theA/C can be used anyway, the utility will not be able to detect it,absent additional verification systems.

One way in which some utilities are seeking to address this issue is tocombine the pager-controlled thermostat with so-called advanced meteringinfrastructure (AMI). This approach relies on the deployment of “smartmeters”—electric meters that are more sophisticated than the traditionalmeter with its mechanical odometer mechanism for logging only cumulativeenergy use. Smart meters generally include a means for communicatinginstantaneous readings. That communication may in the form of a signalsent over the power lines themselves, or a wireless communication over adata network arranged by the utility. These meters allow utilities toaccomplish a number of goals, including offering pricing that varies bytime of day in order to encourage customers to move consumption awayfrom peak demand hours. These smart meters can cost hundreds of dollars,however, and require both a “truck roll”—a visit from a trained serviceperson—and most likely the scheduling of an appointment with theoccupants, because swapping the meter will require turning off power tothe house.

If the utility installs a smart meter at each house that contracts toparticipate in a PDR program, it may be possible to verify that the A/Cis in fact switched off. But this approach requires two separate piecesof hardware, two separate communications systems, and the ability tomatch them for verification purposes.

It would be desirable to have a system that could both implement andverify residential peak demand reduction with reduced expenses.

SUMMARY OF THE INVENTION

At least one embodiment of the invention that includes system forpredicting the rate of change in temperature inside a structurecomprising at least one thermostat located inside the structure andcontrolling an HVAC system in said structure; at least one remoteprocessor that is in communication with said thermostat; at least onedatabase for storing data reported by said thermostat; at least oneprocessor that compares outside temperature at least location and atleast one point in time to information reported to said remote processorfrom said thermostat, and wherein said processor uses the relationshipbetween the inside temperature and the outside temperature over time toderive a first prediction for the rate of change in inside temperatureassuming that the operating status of the HVAC system is “on”; and saidprocessor uses the relationship between the inside temperature and theoutside temperature over time to derive a second prediction for the rateof change in inside temperature assuming that the operating status ofthe HVAC system is “off”; and said processor compares at least one ofthe first prediction and the second prediction to the actual insidetemperature recorded inside the structure to determine whether theactual inside temperature is closer to the first prediction or thesecond prediction.

In one embodiment, the invention comprises a thermostat attached to anHVAC system, a local network connecting the thermostat to a largernetwork such as the Internet, one or more additional thermostatsattached to the network and to other HVAC systems, and a server inbi-directional communication with the thermostats. The server logs theambient temperature sensed by each thermostat vs. time and the signalssent by the thermostats to the HVAC systems to which they are attached.The server preferably also logs outside temperature and humidity datafor the geographic locations for the buildings served by the connectedHVAC systems. Such information is widely available from various sourcesthat publish detailed weather information based on geographic areas suchas by ZIP code. The server also stores other data affecting the loadupon the system, such as specific model of HVAC system, occupancy,building characteristics, etc. Some of this data may be supplied by theindividual users of the system, while other data may come fromcommercial sources such as the electric and other utilities who supplyenergy to those users.

By using these multiple data streams to compare the performance of onesystem versus another, and one system versus the same system at othertimes, the server is able to estimate the effective thermal mass of thestructure, and thereby predict the expected thermal performance of agiven structure in response to changes in outside temperature. Thus, forexample, if the air conditioning is shut off on a hot afternoon, given aknown outside temperature, it will be possible to predict how quicklythe temperature in the house should rise. If the actual temperaturechange is significantly different from the predicted rate of change, ordoes not change at all, it is possible to infer that the airconditioning has not, in fact been shut off.

This and other advantages of the present invention are explained in thedetailed description and claims that make reference to the accompanyingdiagrams and flowcharts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of an overall environment in which an embodimentof the invention may be used.

FIG. 2 shows a high-level illustration of the architecture of a networkshowing the relationship between the major elements of one embodiment ofthe subject invention.

FIG. 3 shows an embodiment of the website to be used as part of thesubject invention.

FIG. 4 shows a high-level schematic of the thermostat used as part ofthe subject invention.

FIG. 5 shows one embodiment of the database structure used as part ofthe subject invention

FIGS. 6A and 6B show a graphical representation of the manner in whichthe subject invention may be used to verify that a demand reductionevent has occurred.

FIG. 7 is a flow chart illustrating the steps involved in generating ademand reduction event for a given subscriber.

FIG. 8 is a flow chart illustrating the steps involved in confirmingthat a demand reduction event has taken place.

FIG. 9 is a representation of the movement of messages and informationbetween the components of the subject invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an example of an overall environment 100 in which anembodiment of the invention may be used. The environment 100 includes aninteractive communication, network 102 with computers 104 connectedthereto. Also connected to network 102 are one or more server computers106, which store information and make the information available tocomputers 104. The network 102 allows communication between and amongthe computers 104 and 106.

Presently preferred network 102 comprises a collection of interconnectedpublic and/or private networks that are linked to together by a set ofstandard protocols to form a distributed network. While network 102 isintended to refer to what is now commonly referred to as the Internet,it is also intended to encompass variations which may be made in thefuture, including changes additions to existing standard protocols.

When a user of the subject invention wishes to access information onnetwork 102, the buyer initiates connection from his computer 104. Forexample, the user invokes a browser, which executes on computer 104. Thebrowser, in turn, establishes a communication link with network 102.Once connected to network 102, the user can direct the browser to accessinformation on server 106.

One popular part of the Internet is the World Wide Web. The World WideWeb contains a large number of computers 104 and servers 106, whichstore HyperText Markup Language (HTML) documents capable of displayinggraphical and textual information. HTML is a standard coding conventionand set of codes for attaching presentation and linking attributes toinformational content within documents.

The servers 106 that provide offerings on the World Wide Web aretypically called websites. A website is often defined by an Internetaddress that has an associated electronic page. Generally, an electronicpage is a document that organizes the presentation of text graphicalimages, audio and video.

In addition to the Internet, the network 102 can comprise a wide varietyof interactive communication media. For example, network 102 can includelocal area networks, interactive television networks, telephonenetworks, wireless data systems, two-way cable systems, and the like.

In one embodiment, computers 104 and servers 106 are conventionalcomputers that are equipped with communications hardware such as modemor a network interface card. The computers include processors such asthose sold by Intel and AMD. Other processors may also be used,including general-purpose processors, multi-chip processors, embeddedprocessors and the like.

Computers 104 can also be handheld and wireless devices such as personaldigital assistants (PDAs), cellular telephones and other devices capableof accessing the network.

Computers 104 utilize a browser configured to interact with the WorldWide Web. Such browsers may include Microsoft Explorer, Mozilla,Firefox, Opera or Safari. They may also include browsers used onhandheld and wireless devices.

The storage medium may comprise any method of storing information. Itmay comprise random access memory (RAM), electronically erasableprogrammable read only memory (EEPROM), read only memory (ROM), harddisk, floppy disk, CD-ROM, optical memory, or other method of storingdata.

Computers 104 and 106 may use an operating system such as MicrosoftWindows, Apple Mac OS, Linux, Unix or the like.

Computers 106 may include a range of devices that provide information,sound, graphics and text, and may use a variety of operating systems andsoftware optimized for distribution of content via networks.

FIG. 2 illustrates in further detail the architecture of the specificcomponents connected to network 102 showing the relationship between themajor elements of one embodiment of the subject invention. Attached tothe network are thermostats 108 and computers 104 of various users.Connected to thermostats 108 are HVAC units 110. The HVAC units may beconventional air conditioners, heat pumps, or other devices fortransferring heat into or out of a building. Each user is connected tothe servers 106 a via wired or wireless connection such as Ethernet or awireless protocol such as IEEE 802.11, a gateway 110 that connects thecomputer and thermostat to the Internet via a broadband connection suchas a digital subscriber line (DSL) or other form of broadband connectionto the World Wide Web. In one embodiment, electric utility server 106 aand demand reduction service server 106 b are in communication with thenetwork 102. Servers 106 a and 106 b contain the content to be served asweb pages and viewed by computers 104, as well as databases containinginformation used by the servers. Also connected to the servers 106 a viathe Internet are computers located at one or more electrical utilities106 b.

In the currently preferred embodiment, the website 200 includes a numberof components accessible to the user, as shown in FIG. 3. Thosecomponents may include a means to store temperature settings 202, ameans to enter information about the user's home 204, a means to enterthe user's electricity bills 206, means to calculate energy savings thatcould result from various thermostat-setting strategies 208, and meansto enable and choose between various arrangements 210 for demandreduction with their electric utility provider as intermediated by thedemand reduction service provider.

FIG. 4 shows a high-level block diagram of thermostat 108 used as partof the subject invention. Thermostat 108 includes temperature sensingmeans 252, which may be a thermistor, thermal diode or other meanscommonly used in the design of electronic thermostats. It includes amicroprocessor 254, memory 256, a display 258, a power source 260, arelay 262, which turns the HVAC system on and off in response to asignal from the microprocessor, and contacts by which the relay isconnected to the wires that lead to the HVAC system. To allow thethermostat to communicate bi-directionally with the computer network,the thermostat also includes means 264 to connect the thermostat to alocal computer or to a wireless network. Such means could be in the formof Ethernet, wireless protocols such as IEEE 802.11, IEEE 802.15.4,Bluetooth, or other wireless protocols. (Other components as needed) Thethermostat 250 may also include controls 266 allowing users to changesettings directly at the thermostat, but such controls are not necessaryto allow the thermostat to function.

The data used to generate the content delivered in the form of thewebsite is stored on one or more servers 106 within one or moredatabases. As shown in FIG. 5, the overall database structure 300 mayinclude temperature database 400, thermostat settings database 500,energy bill database 600, HVAC hardware database 700, weather database800, user database 900, transaction database 1000, product and servicedatabase 1100 and such other databases as may be needed to support theseand additional features.

The website will allow users of connected thermostats 250 to createpersonal accounts. Each user's account will store information indatabase 900, which tracks various attributes relative to users of thesite. Such attributes may include the make and model of the specificHVAC equipment in the user's home; the age and square footage of thehome, the solar orientation of the home, the location of the thermostatin the home, the user's preferred temperature settings, whether the useris a participant in a demand reduction program, etc.

As shown in FIG. 3, the website 200 will permit thermostat users toperform through the web browser substantially all of the programmingfunctions traditionally performed directly at the physical thermostat,such as temperature set points, the time at which the thermostat shouldbe at each set point, etc. Preferably the website will also allow usersto accomplish more advanced tasks such as allow users to program invacation settings for times when the HVAC system may be turned off orrun at more economical settings, and set macros that will allow changingthe settings of the temperature for all periods with a single gesturesuch as a mouse click.

In addition to using the system to allow better signaling and control ofthe HVAC system, which relies primarily on communication running fromthe server to the thermostat, the bi-directional communication will alsoallow the thermostat 108 to regularly measure and send to the serverinformation about the temperature in the building. By comparing outsidetemperature, inside temperature, thermostat settings, cycling behaviorof the HVAC system, and other variables, the system will be capable ofnumerous diagnostic and controlling functions beyond those of a standardthermostat.

For example, FIG. 6 a shows a graph of inside temperature, outsidetemperature and HVAC activity for a 24 hour period. When outsidetemperature 302 increases, inside temperature 304 follows, but with somedelay because of the thermal mass of the building, unless the airconditioning 306 operates to counteract this effect. When the airconditioning turns on, the inside temperature stays constant (or risesat a much lower rate) despite the rising outside temperature. In thisexample, frequent and heavy use of the air conditioning results in onlya very slight temperature increase inside o the house of 4 degrees, from72 to 76 degrees, despite the increase in outside temperature from 80 to100 degrees.

FIG. 6 b shows a graph of the same house on the same day, but assumesthat the air conditioning is turned off from noon to 7 PM. As expected,the inside temperature 304 a rises with increasing outside temperatures302 for most of that period, reaching 88 degrees at 7 PM.

Because server 106 a logs the temperature readings from inside eachhouse (whether once per minute or over some other interval), as well asthe timing and duration of air conditioning cycles, database 300 willcontain a history of the thermal performance of each house. Thatperformance data will allow the server 106 a to calculate an effectivethermal mass for each such structure—that is, the speed with thetemperature inside a given building will change in response to changesin outside temperature. Because the server will also log these inputsagainst other inputs including time of day, humidity, etc. the serverwill be able to predict, at any given time on any given day, the rate atwhich inside temperature should change for given inside and outsidetemperatures.

As shown in FIG. 3, website 200 will allow the users to opt 210 into aplan that offers incentives such as cash or rebates in exchange forreduced air conditioning use during peak load periods.

FIG. 7 shows the steps followed in order to initiate air conditionershutoff. When a summer peak demand situation occurs, the utility willtransmit an email 402 or other signal to server 106 a requesting areduction in load. Server 106 a will determine 404 if the user's houseis served by the utility seeking reduction; determine 406 if a givenuser has agreed to reduce peak demand; and determine 408 if a reductionof consumption by the user is required or desirable in Order to achievethe reduction in demand requested by the utility. The server willtransmit 410 a signal to the user's thermostat 108 signaling thethermostat to shut off the air conditioner 110.

FIG. 8 shows the steps followed in order to verify that the airconditioner has in fact been shut off. Server 106 a will receive andmonitor 502 the temperature readings sent by the user's thermostat 108.The server then calculates 504 the temperature reading to be expectedfor that thermostat given inputs such as current and recent outsidetemperature, recent inside temperature readings, the calculated thermalmass of the structure, temperature readings in other houses, etc. Theserver will compare 506 the predicted reading with the actual reading.If the server determines that the temperature inside the house is risingat the rate predicted if the air conditioning is shut off, then theserver confirms 508 that the air conditioning has been shut off. If thetemperature reading from the thermostat shows no increase, orsignificantly less increase than predicted by the model, then the serverconcludes 510 that the air conditioning was not switched off, and thatno contribution to the demand response request was made.

For example, assume that on at 3 PM on date Y utility X wishes totrigger a demand reduction event. A server at utility X transmits amessage to the server at demand reduction service provider Z requestingW megawatts of demand reduction. Demand reduction service providerserver determines that it will turn off the air conditioner at house Ain order to achieve the required demand reduction. At the time the eventis triggered, the inside temperature as reported by the thermostat inhouse A is 72 degrees F. The outside temperature near house A is 96degrees Fahrenheit. The inside temperature at House B, which is not partof the demand reduction program, but is both connected to the demandreduction service server and located geographically proximate to HouseA, is 74 F. Because the A/C in house A has been turned off, thetemperature inside House A begins to rise, so that at 4 PM it hasincreased to 79 F. Because the server is aware of the outsidetemperature, which remains at 96 F, and of the rate of temperature riseinside house A on previous days on which temperatures have been at ornear 96 F, and the temperature in house B, which has risen only to 75 Fbecause the air conditioning in house B continues to operate normally,the server is able to confirm with a high degree of certainty that theNC in house A has indeed been shut off.

In contrast, if the HVAC system at house A has been tampered with, sothat a demand reduction signal from the server does not actually resultin shutting off the NC in house A, when the server compares the rate oftemperature change at house A against the other data points, the serverwill receive data inconsistent with the rate of increase predicted. As aresult, it will conclude that the A/C has not been shut off in house Aas expected, and will not credit house A with the financial credit thatwould be associated with demand reduction compliance, or may trigger abusiness process that could result in termination of house A′sparticipation in the demand reduction program.

FIG. 9 illustrates the movement of signals and information between thecomponents of the subject invention to trigger and verify a demandreduction response. In step 602 the electric utility server 106 btransmits a message to demand reduction service server 106 a requestinga demand reduction of a specified duration and size. Demand reductionservice server 106 a uses database 300 to determine which subscribersshould be included in the demand reduction event. For each includedsubscriber, the server then sends a signal 604 to the subscriber'sthermostat instructing it (a) to shut down at the appropriate time or(b) to allow the temperature as measured by the thermostat to increaseto a certain temperature at the specified time, depending upon theagreement between the homeowner and the demand reduction aggregator. Theserver then receives 606 temperature signals from the subscriber'sthermostat. At the conclusion of the demand reduction event, the servertransmits a signal 608 to the thermostat permitting the thermostat tosignal its attached HVAC system to resume cooling, if the system hasbeen shut off, or to reduce the target temperature to its pre-demandreduction setting, if the target temperature was merely increased. Afterdetermining the total number of subscribers actually participating inthe DR event, the server then calculates the total demand reductionachieved and sends a message 610 to the electric utility confirming suchreduction.

Additional steps may be included in the process. For example, if thesubscriber has previously requested that notice be provided when a peakdemand reduction event occurs, the server will also send an alert, whichmay be in the form of an email message or an update to the personalizedweb page for that user, or both. If the server determines that a givenhome has (or has not) complied with the terms of its demand reductionagreement, the server will send a message to the subscriber confirmingthat fact.

It should also be noted that in some climate zones, peak demand eventsoccur during extreme cold weather rather than (or in addition to) duringhot weather. The same process as discussed above could be employed toreduce demand by shutting off electric heaters and monitoring the rateat which temperatures fall.

It should also be noted that the peak demand reduction service can beperformed directly by a power utility, so that the functions of server106 a can be combined with the functions of server 106 b.

The system installed in a subscriber's home may optionally includeadditional temperature sensors at different locations within thebuilding. These additional sensors may we connected to the rest of thesystem via a wireless system such as 802.11 or 802.15.4, or may beconnected via wires. Additional temperature and/or humidity sensors mayallow increased accuracy of the system, which can in turn increase usercomfort, energy savings or both.

While particular embodiments of the present invention have been shownand described, it is apparent that changes and modifications may be madewithout departing from the invention in its broader aspects and,therefore, the invention may carried out in other ways without departingfrom the true spirit and scope. These and other equivalents are intendedto be covered by the following claims:

1. A system for monitoring the operational status of an HVAC systemcomprising: at least one HVAC control system associated with a firststructure that receives temperature measurements from at least a firststructure conditioned by at least one HVAC system; one or moreprocessors that receive measurements of outside temperatures from atleast one source other than said HVAC system, wherein said one or moreprocessors compares the inside temperature of said first structure andthe outside temperature over time to derive an estimation for the rateof change in inside temperature of said first structure assuming thatthe operating status of the first HVAC system is “off”, and wherein saidone or more processors compare an inside temperature recorded inside thefirst structure with said estimation for the rate of change in insidetemperature of said first structure assuming that the operating statusof the first HVAC system is “off” to determine whether the first HVACsystem is on or off.
 2. A system as in claim 1 in which said one or moreprocessors receive measurements of outside temperatures for geographicregions such as ZIP codes from sources other than said HVAC system.
 3. Asystem as in claim 1 in which said HVAC system is located within asingle family dwelling.
 4. A system as in claim 1 in which said HVACsystem comprises a programmable thermostat.
 5. A system as in claim 1 inwhich said HVAC system comprises a programmable thermostat thatcommunicates with said system using a mesh networking protocol.
 6. Asystem as in claim 1 in which said HVAC system comprises a programmablethermostat that communicates with said system using the Internet.
 7. Asystem as in claim 1 in which said one or more processors communicatewith said HVAC system using a network that includes an electricitymeter.
 8. A system as in claim 1 in which said estimation is aprediction about the future rate of change in temperature inside saidstructure.
 9. A method for monitoring the operation of an HVAC systemcomprising: receiving temperature measurements from at least one HVACcontrol system associated with a first structure conditioned by at leastone HVAC system; receiving at one or more processors, measurements ofoutside temperatures from at least one source other than said HVACsystem; comparing with said one or more processors the insidetemperature of said first structure and the outside temperature overtime to derive an estimation for the rate of change in insidetemperature of said first structure assuming that the operating statusof the first HVAC system is “off”, and comparing with said one or moreprocessors, an inside temperature recorded inside the first structurewith said estimation for the rate of change in inside temperature ofsaid first structure assuming that the operating status of the firstHVAC system is “off” to determine whether the first HVAC system is on oroff.
 10. A method as in claim 9 in which said one or more processorsreceive measurements of outside temperatures for geographic regions suchas ZIP codes from sources other than said HVAC system.
 11. A method asin claim 9 in which said HVAC system is located within a single familydwelling.
 12. A method as in claim 9 in which said HVAC system comprisesa programmable thermostat.
 13. A method as in claim 9 in which said HVACsystem comprises a programmable thermostat that communicates with saidsystem using a mesh networking protocol.
 14. A method as in claim 9 inwhich said HVAC system comprises a programmable thermostat thatcommunicates with said system using the Internet.
 15. A method as inclaim 9 in which said one or more processors communicate with said HVACsystem using a network that includes an electricity meter.
 16. A methodas in claim 9 in which said estimation is a prediction about the futurerate of change in temperature inside said structure.